CN100478287C - Film coating method of filling material in biological contact oxidation pond - Google Patents

Abstract

The invention provides a film-hanging method for fillers in a biological contact oxidation tank to solve the technical problems of long biofilm-hanging time, uneven distribution of biofilm, poor fixation degree and the like in wastewater treated by biofilm method. The basic content of the present invention is: first domesticate the activated sludge, then add the nutrient solution to the domesticated activated sludge and the waste water mixture to be treated, mix it and pour it into the oxidation tank equipped with fillers for aeration and circular cultivation, Let the microorganisms attach to the carrier, then let it settle for a period of time, and then completely drain the mud-water mixture in the oxidation tank, and start to continuously cultivate the wastewater from low concentration to high concentration until a stable impact-resistant biofilm is formed. Its characteristic is to strengthen the adhesion ability of microorganisms on the filler, shorten the time of biofilm formation, and make the mature biofilm resistant to impact load.

Description

Film-hanging method of filler in biological contact oxidation pond

Technical field:

The invention relates to biological treatment of waste water, in particular to a biofilm method for treating waste water, in particular to a film-hanging method for fillers in biological contact oxidation tanks.

Background technique:

The key to biofilm treatment of wastewater is the growth of microorganisms on the carrier in the oxidation tank, that is, the degree of fixation of the biofilm on the carrier and the activity of microorganisms, which mainly depends on the properties of the carrier material and the combination of the organism and the carrier (that is, the biofilm) ). At present, most people pay attention to the research on the type and structure of the biological carrier, and there have been a large number of literature reports and patent reports. The literature reports on the research on the biofilm-hanging methods mainly include "stuffy exposure method", "circular film-hanging method", There are four kinds of "rapid sludge removal method" and "natural film method", but each has certain defects. In "Experimental Research on Biomembrane Reactor Film Hanging Method" (comparative literature 1) published in "China Water Supply and Drainage" magazine, No. 8, No. 3, Volume 8 in 1992, Yu Hanqing proposed the method of fast sludge discharge and film hanging, and proved that it is more effective than The cycle hanging film method is more superior. Yuan Junfeng pointed out in the paper "A New Film-hanging Method for Aerated Biological Filter Reactor" (comparative literature 2) in the "Environmental Engineering" magazine, Volume 21, No. 2, 2003, that: The fixation degree of the biofilm is not very good, and it is easy to fall off when the impact load is large, especially when it is backwashed, resulting in a long recovery period and even re-hanging of the film. In Wang Guanping's "Factors Influencing Film Formation in Pretreatment Biofilters" published in the 19th issue of 2003 in the "China Water Supply and Drainage" magazine (compared with literature 3), he believes that the artificial inoculation method of film formation has a short period of time and bacteria are easy to grow. Recession, poor reactor stability. The natural film-hanging method uses natural enrichment to cultivate biofilms, which takes a long time, usually 1 to 2 months. There are few relevant patent reports. The patent "A Method for Improving the Performance of Suspended Filler Biofilms" invented by Ma Luming et al. Added the catalytic iron internal electrolysis method as the pretreatment section of the biological suspension filler process, and adopted different aeration methods according to the oxidation-reduction potential and pH value of industrial wastewater. This patent is mainly aimed at the biological treatment of suspended fillers and industrial wastewater, adding an internal electrolysis section.

From comparative literature 1, 2, and 3, it can be seen that the currently reported biofilm method has the disadvantages of long time, complicated operation, and low impact load resistance, which makes the growth of microorganisms on the carrier poor, which leads to the biofilm method for wastewater treatment. The effect is not ideal. However, compared with literature 4, the treatment effect of wastewater after filming is better, but it needs to increase the internal electrolysis device, and the operation is complicated. Therefore, it is meaningful to study a simple and fast biofilm method.

Invention content:

The object of the present invention is to provide a biofilm-hanging method for fillers in biological contact oxidation tanks with short time for biofilm-hanging, good growth and fixation degree of microorganisms, and impact load resistance.

The basic content of the present invention is as follows: first domesticate the activated sludge, then add nutrient solution to the domesticated activated sludge and the waste water to be treated, inject it into an oxidation tank equipped with fillers to carry out aeration and circular culture, so that the microorganisms in the carrier After that, let it settle for a period of time, and then completely drain the mud-water mixture in the oxidation tank, and start to continuously feed wastewater from low concentration to high concentration for cultivation until a stable impact-resistant biofilm is formed.

The film-hanging method of filler in the biological contact oxidation tank provided by the invention comprises the following steps successively:

(1) Take the activated sludge to be treated for waste water, aerate and cultivate at room temperature for 1 to 2 days, control the SV ₃₀ to 25% to 35%, and the sludge mass concentration is about 5000mg/L-9000mg/L;

(2) Mix the cultivated and domesticated sludge with the wastewater to be treated at a volume ratio of 1:2-4, and add a nutrient solution with a volume of 2 to 4% of the mud-water mixture, mix the nutrient solution and the mud-water mixture, and then partially inject the oxidation The filler is completely submerged in the tank, and the rest is poured into the circulation tank; the concentration of dissolved oxygen in the oxidation tank is controlled at 1-2mg/L and aerated for 6-8 hours at room temperature, so that the sludge and the filler can fully contact to inoculate microorganisms;

(3) After the aeration process is over, the mixed solution in the circulation tank is continuously pumped into the oxidation tank, and at the same time, the overflow water from the oxidation tank flows into the circulation tank, and the cycle is like this for 20-26 hours;

(4) leave it to settle for 1-2 hours, then the mud-water mixture in the oxidation tank is all drained, at this moment there is a small amount of sessile microorganisms on the carrier;

(5) Start to continuously feed water into the oxidation tank with 50% to 70% of the hydraulic load during normal operation and 50% to 60% of the organic load during normal treatment, and then gradually increase the hydraulic load and organic load, and increase the aeration amount until a stable biofilm is formed on the carrier in the oxidation tank.

The control conditions in the step (1) are preferably SV ₃₀ is 30%, sludge mass concentration is 6000mg/L-7000mg/L.

The fillers can be various fillers suitable for biological contact oxidation tanks, such as fixed fillers, suspended fillers, dispersed fillers, suspended fillers or soft, semi-soft, composite fillers, etc., and the suspension type semi-soft fillers are preferred in the test. Soft spherical plastic filler.

Described nutrient adopts the nutrient added in conventional wastewater treatment, C source can adopt glucose or/and starch, N source can adopt urea, P source can adopt phosphate, after adding, make C:N:P= 100:5:1.

Advantages and beneficial effects of the film-hanging method of the present invention:

(1) Sludge domestication before film formation. Ensure that there is a sufficient amount of microorganisms in the oxidation tank when the film is formed, and it is suitable for growth in the environment of the target wastewater, so that the microorganisms in the bacterial solution can more fully adhere to the solid phase filler.

(2) Add nutrients. Maintaining sufficient nutrient mechanism in the oxidation pool can enable microorganisms to reproduce at a high speed, and at the same time further increase the amount of microorganisms attached to the carrier.

(3) After the mud-water mixture is added to the oxidation tank, it is first aerated. The agitation of the air can accelerate the contact area between the microorganisms in the sludge and the filler, and increase the attachment speed of the microorganisms.

(4) Circulation after the aeration is completed can make the microorganisms and the filler contact again to the greatest extent, thereby increasing the microbial mass on the filler.

(5) After the aeration and circulation process is completed, all the suspended microorganisms in the oxidation tank are discharged. Because the suspended microorganisms and the sessile microorganisms are a coexistence of trade-offs, they compete for nutrients in the oxidation pool to satisfy their own growth. Therefore, during the film-hanging period, try to reduce the number of suspended microorganisms in the oxidation tank, then the fixed-state microorganisms will multiply rapidly, and the best film-hanging effect can be achieved.

(6) After the cycle process is over, water is fed into the oxidation tank from a low organic load and hydraulic load to give a certain buffer period for microbial growth, and then gradually increase the hydraulic load and organic load. Otherwise, too high influent concentration will cause biofilm to quickly accumulate on the surface of the filler, which is not conducive to the adsorption of microorganisms and the formation of a uniform biofilm on the surface of the filler. In addition, by gradually increasing the aeration intensity, the sessile organisms attached to the carrier can adapt to strong impact loads, so the formed biofilm is more resistant to impact loads.

Description of drawings:

Figure 1 is a schematic diagram of the operation mode of the oxidation tank in the aeration stage of the film-hanging process

Figure 2 is a schematic diagram of the operation mode of the oxidation tank in the circulation stage after the aeration stage of the film-hanging process

Figure 3 is a schematic diagram of the operation mode of the oxidation tank in the water inlet stage after the cycle stage of the film hanging process is over

Detailed ways

Example 1:

The test uses a biological contact oxidation tank with a volume of 13 liters to treat domestic wastewater. The filler is a suspended semi-soft spherical plastic filler. The temperature of the test environment is 26°C, the pH of the wastewater is 6.8, and the sludge is taken from the secondary sedimentation tank of a domestic sewage plant. The return sludge in the sludge has a SV ₃₀ =30% and a mass density of 7000 mg/L after acclimatization.

Mix the cultivated sludge with domestic waste water at a volume ratio of 1:3, and add 300ml of nutrients according to the ratio of C:N:P=100:5:1 (see Table 1 below for the formula of the nutrient solution), and then mix the mixture Inject into the oxidation tank to fully submerge the filler, pour the rest into the circulation tank, control DO=1.0mg/L in the oxidation tank at room temperature, and aerate for 6 hours as shown in Figure 1. Then connect the oxidation tank to the circulation tank, keep the aeration rate unchanged, and after 24 hours of circular operation as shown in Figure 2, discharge all the mixed liquid in the oxidation tank, and start to follow the steps shown in Figure 3, first with a flow rate of 1L/h Continuously enter domestic wastewater, the concentration of COD in the influent is about 280mg/L, the concentration of NH ₃ -N is about 22mg/L, and after two days, the flow rate of the influent gradually increases to 2L/h, the concentration of COD is 580mg/L, and the concentration of NH ₃ -N The concentration is 40mg/L, and the amount of aeration and water intake should be increased accordingly.

Three days after starting to treat the wastewater, the COD removal rate of the wastewater reached 80%, the NH ₃ -N removal rate was ≥70%, and the microscopic examination showed that the microorganisms grew well. The appearance of the filler gradually changes from muddy yellow-yellow-brown to deep yellow-brown. All indicators prove that the biofilm obtained by this method is stable and has good wastewater treatment capacity.

Table 1 nutrient solution ratio

Component name Amount added Component name Amount added starch 36/g (NH₄)₂CO₃ 22.4/g Glucose 22/g K₂HPO₃ 8.8/g tap water 5/L

Example 2:

The industrial waste water from the anaerobic tank of a certain coking plant is used as test water, and the test operating conditions and steps are the same as in Example 1.

After four days of water inflow, the COD removal rate of the wastewater is ≥60%, the NH ₃ -N removal rate is ≥50%, and the microorganisms grow well under the microscope. One week later, it was found that there were filamentous bacteria growing on the edge of the filler, and there were many protozoa and metazoans such as paramecia, rotifers, nematodes, bell worms and so on. The biofilm close to the center of the filler was observed through a microscope and found to have more cocci, bacilli, bacterial gelatinous groups and a large number of bell worms. All the indicators prove that the biofilm obtained by this method is stable and has good wastewater treatment capacity.

Example 3:

The test adopts a biological contact oxidation tank with a volume of 24 liters to treat domestic wastewater, and the test operating conditions and steps are the same as in Example 1.

Three days after entering the water, the film was successfully formed. The COD removal rate of the wastewater reached 80%, and the NH ₃ -N removal rate was ≥70%. Microscopic examination of the biological phase on the surface of the filter material found that the sticky sludge on it was mainly bell Insects, rotifers, paramecia, and other cladeworms and other protozoa or metazoans, indicating that the growth of biofilm on the filter material has been relatively complete. And in the later stage of the test, the amount of water inflow was increased (HRT was reduced from the initial 12h to 4h), and the degree of erosion of the biofilm on the filler by the water flow was increased. The test shows that the removal rate of COD and NH ₃ -N in wastewater does not change much, the growth of microorganisms on the biofilm is firm, and the amount of biofilm is stable.

Claims (2)

1, the colonization method of filler in a kind of biological contact oxidation pond is characterized in that in turn including the following steps:

(1) gets the active sludge aeration cultivation at room temperature that to handle waste water and tamed control SV 1～2 day ₃₀Be 25%～35%, the active sludge mass concentration is 5000mg/L-9000mg/L;

(2) will cultivate the good active sludge of domestication and waste water to be processed by volume 1: 2-4 mixes, and the nutritive medium of adding active sludge and waste water mixture volume 2～4% to be processed, with nutritive medium and active sludge and the complete submergence filler of waste water mixture mixing to be processed rear section injection oxidation pond, the remaining circulatory pool of pouring into; Under the room temperature in the controlled oxidation pond dissolved oxygen concentration be 1～2mg/L aeration 6～8 hours;

(3) treat that aeration process finishes after, the mixed solution in the circulatory pool is pumped into oxidation pond, the water outlet of simultaneous oxidation pond flows into circulatory pool, so circulates 20-26 hour;

(4) standing sedimentation 1-2 hour, then mud mixture in the oxidation pond is all drained;

(5) beginning organic loading water inlet of 50%～60% when 50%～70% hydraulic load and normal processing during continuously with normal operation in oxidation pond, strengthen hydraulic load and organic loading then gradually, and the increase aeration rate, in oxidation pond, form microbial film on the carrier.

2, colonization method as claimed in claim 1 is characterized in that, control SV in the described step (1) ₃₀Be 30%, sludge quality concentration is 6000mg/L-7000mg/L.

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